Creating a vCenter snapshot in Enhanced Linked Mode (ELM)
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Creating a vCenter snapshot in Enhanced Linked Mode (ELM)

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Article ID: 443102

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Updated On:

Products

VMware vCenter Server

Issue/Introduction

When attempting to take a snapshot of a vCenter Server Appliance (VCSA) that participates in an Enhanced Linked Mode (ELM) configuration, taking independent or online snapshots introduces a critical risk of replication inconsistency. If a single node is reverted independently, it can cause sequence number mismatches and replication partner isolation within the VMware Directory Service (VMDIR) database, leading to environment-wide authentication and management failures.

Environment

  • VMware vCenter Server 7.x
  • VMware vCenter Server 8.x

Cause

Replicating directory databases (VMDIR) in Enhanced Linked Mode cannot automatically reconcile state differences if a single node is rolled back to an online snapshot while other nodes continue changing the global registry (licenses, permissions, tags). Offline, simultaneous snapshots across all nodes are required to preserve multi-node database consistency.

Resolution

CRITICAL WARNING: vCenters in Enhanced Linked Mode (ELM) share a joint Platform Services Controller (PSC) database. Snapshotting and restoring just one vCenter in an ELM replication group will break the replication ring, corrupt the database, and likely ruin the environment.

To take snapshots in ELM safely, a simultaneous, cold snapshot must be taken of all vCenters in that replication group.

Step 1: Identify All Members and Hosts

  1. Identify every single vCenter that belongs to the ELM environment.

  2. Determine exactly which ESXi hosts are running these vCenter VMs. Log into each of those ESXi hosts directly.

Step 2: Shut Down ALL vCenters Simultaneously

  1. Coordinate a maintenance window (this will cause complete management downtime).

  2. Go to each ESXi host and Shut Down every vCenter VM in the ELM group.

  3. Do not proceed until all of them are completely powered off.

Step 3: Take Snapshots of All vCenters

  1. On their respective ESXi hosts, right-click each vCenter VM.

  2. Select Snapshots > Take Snapshot.

  3. Use the exact same naming convention for all of them to remember they are linked (e.g., ELM_Maintenance_Part1, ELM_Maintenance_Part2).

  4. Ensure memory snapshot is unchecked.

  5. Create the snapshots.

Step 4: Power On and Verify

  1. Power all the vCenter VMs back on.

  2. Allow ample time for the services to boot up and for the replication partners to talk to each other again.

Additional Information

For more information about vCenter ELM snapshots, see VMware vCenter in Enhanced Linked Mode pre-changes snapshot (online or offline) best practice

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